Boat drain plug



FIG. 1 is a front elevational view of a boat drain plug showing my new design;

FIG. 2 is a side elevational view thereof, the opposidte side being a mirror image of that shown;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof.

The broken line showing of environmental structure in FIGS. 1-5 is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a boat drain plug, as shown and described. 